The present invention relates to a machine vise. More particularly, this invention relates to a machine vise for grasping a given work blank between parallel jaw plates of a pair of stationary and movable jaws which parallel jaw plates constantly keep their postural angle at a right angle relative to the surface of the slide for the movable jaw.
A vise of the type comprising a stationary jaw fixed in position on a vise bed and a movable jaw mounted on the vise bed in a manner capable of free straight movement toward and away from the stationary jaw so as to be capable of grasping a given article between the parallel jaw plates of the jaws is known to the art. The vise disclosed by Japanese Patent Publication No. Sho-47(1972)-33960 is one example of this type of vise.
One fault common to all vises of this type is the fact that a given article, when grasped by being clamped between the jaws, inclines toward the movable jaw. In machine vises, the normality (expressed in terms of inward angular deviation from a right angle) of the opposed surfaces of the parallel jaw plates relative to the surface of the slide for the movable jaw is preferably not more than 0.03 mm per 100 mm in height of the jaws. The angle of the inclination of the article toward the movable jaw conspicuously differs when the article is grasped in the upper portion of the jaws and when it is grasped in the middle portion of the jaws. Further, there is some possibility that the shape of the article will make it quite difficult to grasp the article between the jaws in a state wherein the parallel jaw plates of the jaws keep their postural angle constantly at a right angle relative to the surface of the slide for the movable jaw. For this reason, in the actual maching operation, a skilled machinist attempts to maintain the jaw plates of the jaws at a right angle relative to the surface of the slide for the movable jaw as by observing the established practice of strongly clamping a given article and hitting the article with a hammer to bring the article into intimate contact with the surface of the slide for the movable jaw in the course of coarse cutting to permit removal of large cuts and, conversely in the subsequent course of fine cutting, weakly clamping the article to permit removal of fine cuts. This practice, however, lacks stability and reliability in the sense that it totally relies on the individual machinist's experience and skill. Some, if not all, articles given to be worked may possibly fail to remain fast in position when they are grasped weakly and, therefore, defy all efforts to give a desired cutting thereto. Depending on the condition of the clamping of an article between the jaws, even a vise of high accuracy is not free from the possibility of yielding an inferior product which is rejectable in terms of dimensional accuracy. There is another possibility that the rigidity which the vise as a whole exhibits when a given article is grasped thereby will fall short of the required level and, as a result, the cutting tool will have its service life greatly shortened.
An object of this invention is to provide a machine vise adapted to permit an article subjected to machining to be grasped between the stationary jaw and the movable jaw in a state wherein the jaw plates of the jaws constantly keep their postural angle at a right angle relative to the surface of the slide for the movable jaw without causing the article to rise off the sliding surface when grasped.
Another object of this invention is to provide a machine vise notably improved in structural strength and rigidity to provide enhanced durability.